Air bag module with actuatable vent part

ABSTRACT

An apparatus ( 10 ) for helping to protect an occupant of a vehicle includes an inflatable vehicle occupant protection device ( 14 ). An inflation fluid source ( 18 ) is actuatable to provide inflation fluid for inflating an inflatable volume ( 16 ) of the protection device ( 14 ). The apparatus ( 10 ) also includes a reaction plate ( 20 ) that includes at least one vent opening ( 40 ) and a retainer ( 60 ) that is connectable with the reaction plate ( 20 ). A vent part ( 80 ) has a first condition blocking inflation fluid flow through the at least one vent opening ( 40 ) and a second condition permitting inflation fluid flow through the at least one vent opening. The apparatus ( 10 ) further includes an actuator ( 120 ) for moving the vent part ( 80 ) from one of the first and second conditions to the other of the first and second conditions. The vent part ( 80 ) has a portion ( 104 ) that maintains the vent part in the other of the first and second conditions when moved to the other of the first and second conditions.

FIELD OF THE INVENTION

The present invention relates to a vehicle occupant protectionapparatus. In particular, the present invention relates to an air bagmodule including a vent for releasing inflation fluid from the air bag.

BACKGROUND OF THE INVENTION

It is known to inflate an inflatable vehicle occupant protection deviceto help protect a vehicle occupant in the event of a vehicle collision.One particular type of inflatable vehicle occupant protection device isa front air bag inflatable by inflation fluid directed into the air bagfrom an inflator. A driver side front air bag is inflated from a storedposition in a vehicle steering wheel to a deployed position between anoccupant of a front driver side seat and the steering wheel andinstrument panel of the vehicle. A passenger side front air bag isinflated from a stored position in the instrument panel to a deployedposition between an occupant of a front passenger side seat and theinstrument panel.

Another type of inflatable vehicle occupant protection device is aninflatable curtain that inflates from the roof of the vehicle downwardinside the passenger compartment between a vehicle occupant and the sidestructure of the vehicle in the event of a side impact or rollover. Aknown inflatable curtain is inflated from a deflated condition byinflation fluid directed from an inflator to the inflatable curtainthrough a fill tube.

Yet another type of inflatable vehicle occupant protection device is aside impact air bag inflatable between the side structure of the vehicleand a vehicle occupant. Side impact air bags may be stored in a varietyof locations in the vehicle, such as the side structure, seat, door, orfloor of the vehicle. A side impact air bag may be inflated by inflationfluid directed into the air bag from an inflator. Other types ofinflatable vehicle occupant protection devices include inflatable seatbelts and inflatable knee bolsters.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus for helping to protect anoccupant of a vehicle that includes an inflatable vehicle occupantprotection device. An inflation fluid source is actuatable to provideinflation fluid for inflating an inflatable volume of the inflatablevehicle occupant protection device. The apparatus also includes areaction plate that includes at least one vent opening and a retainerthat is connectable with the reaction plate. A vent part has a firstcondition blocking inflation fluid flow through the vent opening and asecond condition permitting inflation fluid flow through the ventopening. The apparatus further includes actuatable means for moving thevent part from one of the first and second conditions to the other ofthe first and second conditions. The vent part has a portion thatmaintains the vent part in the other of the first and second conditionswhen moved to the other of the first and second conditions.

The present invention also relates to an air bag module including an airbag and a reaction plate including at least one vent opening. A retaineris connectable with the reaction plate to clamp the air bag between thereaction plate and the retainer. The retainer includes a vent parthaving a first condition blocking inflation fluid flow through the ventopening and a second condition permitting inflation fluid flow throughthe vent opening. An actuatable fastener has a first portion secured tothe reaction plate and a second portion secured to the vent part. Theactuatable fastener is actuatable to move the vent part from one of thefirst and second conditions to the other of the first and secondconditions.

The present invention further relates to an air bag module including anair bag and a reaction plate including at least one vent opening. Aretainer, connectable with the reaction plate, includes a vent partformed as a single piece of material with the retainer. The vent part isat least partially defined by a slit extending through the retainer. Thevent part has a first condition blocking inflation fluid flow throughthe vent opening and a second condition permitting inflation fluid flowthrough the vent opening.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present invention will becomeapparent to one skilled in the art to which the present inventionrelates upon consideration of the following description of the inventionwith reference to the accompanying drawings, in which:

FIG. 1 is a side view, partially in section, of an apparatus includingan inflatable vehicle occupant protection device in a deflated andstored condition and a vent in a closed condition, according to a firstembodiment of the present invention;

FIG. 2 is a view of the apparatus of FIG. 1 illustrating the inflatablevehicle occupant protection device in an inflated and deployed conditionand the vent in an open condition;

FIG. 3 is a plan view of a reaction plate portion of the apparatus ofFIGS. 1 and 2;

FIG. 4 is a plan view of a retainer portion of the apparatus of FIGS. 1and 2;

FIGS. 5A and 5B are magnified views of a portion of the apparatus ofFIGS. 1 and 2, respectively;

FIG. 6 is a plan view of a vent part construction for the apparatus,according to a second embodiment of the present invention; and

FIGS. 7A and 7B are magnified views of a portion of the apparatusincluding the alternative vent part of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an apparatus for helping to protect anoccupant of a vehicle. In particular, the present invention relates toan inflatable vehicle occupant protection device module that has a ventthat is actuatable from a closed condition to an open condition to ventinflation fluid from the protection device.

As representative of the invention, FIGS. 1 and 2 illustrateschematically an apparatus 10 for helping to protect an occupant of avehicle (not shown). In the embodiment of FIGS. 1 and 2, the apparatus10 comprises an air bag module 12 that includes an inflatable occupantprotection device in the form of an air bag 14. The apparatus 10 could,however, comprise other vehicle occupant protection devices that can beused in accordance with the invention. For example, the apparatus 10could comprise inflatable seat belts, inflatable knee bolsters,inflatable head liners, inflatable side curtains, and knee bolstersoperated by inflatable air bags.

The air bag module 12 of the illustrated embodiment is a front impactair bag module mountable on a driver side or passenger side of avehicle. For example, in a driver side implementation, the air bagmodule 12 may be mounted on a steering wheel of the vehicle. In apassenger side implementation, the air bag module 12 may be mounted inan instrument panel of the vehicle.

The air bag 14 is preferably made from a flexible fabric material, suchas woven nylon, and has an inflatable volume 16. The nylon may be coatedwith a gas impermeable material, such as urethane, or laminated with agas impermeable film. The air bag 14 thus may have a substantiallygas-tight construction. Those skilled in the art will appreciate thatalternative materials, such as woven polyester, and alternativescoatings, such as silicone, may also be used to construct the air bag14.

The air bag module 12 includes an inflator 18 for inflating the air bag14. The inflator 18 may contain a stored quantity of pressurizedinflation fluid and an ignitable material for heating the inflationfluid. The air bag module 12 alternatively could include an inflator 18that uses the combustion of gas generating material to generateinflation fluid in the form of gas to inflate the air bag 14. As anotheralternative, the inflator 18 may contain only a stored quantity ofpressurized inflation fluid for inflating the air bag 14. As a furtheralternative, the inflator 18 could be of any suitable type for supplyinga medium for inflating the air bag 14.

The inflator 18 and the air bag 14 are supported on a support member 20.The support member 20 is a member or assembly that is fixed in positionon the vehicle, that supports the inflator 18 and the air bag 14, andthat receives the reaction forces of the inflator and the air bag whenthe inflator is actuated. In the illustrated embodiment, the supportmember 20 is a reaction plate.

The reaction plate 20 is illustrated in FIG. 3. Referring to FIGS. 1-3,the reaction plate 20 is a single piece of material, such as metal orhigh strength plastic, that is formed to the illustrated configuration.It will be appreciated that the reaction plate 20 could have a varietyof alternative configurations depending on various factors, such as thearchitecture of the vehicle in which the air bag module 12 is installed.

The reaction plate 20 has a main portion 22 with a rim or outer wall 24that extends about a periphery 26 of the reaction plate in a directiondownward (as viewed in FIGS. 1 and 2) from the main portion 22. Thereaction plate 20 may also include tabs 30 spaced about the periphery 26of the main portion 22 that project in the same downward direction fromthe outer wall 24. The tabs 30 may interface with portions of a vehicle(not shown) to help secure the module 10 in the vehicle. The tabs 30 mayinclude apertures 32 for receiving fasteners (not shown) for furtherhelping to secure the air bag module 12 in the vehicle.

The main portion 22 also includes a central opening 34 for receiving aportion of the inflator 18. In the embodiment of FIGS. 1-3, the centralopening 34 has a generally circular configuration to receive acylindrical portion 36 of the inflator 18. The central opening 34 could,however, have a different configuration for matching an inflator havinga different construction.

The reaction plate 20 also includes vent openings 40 for releasinginflation fluid from the air bag module 12. In the embodiment shown inFIG. 3, the reaction plate 20 includes a pair of vent openings 40positioned on opposite sides of an actuator receiving opening 42. Thevent openings 40 have a contoured wing-shaped configuration arranged ina mirror-image fashion. The configuration, number, and arrangement ofthe vent openings on the reaction plate 20 could, however, be altered toprovide a desired venting effect.

The reaction plate 20 also includes apertures 44 for cooperating withfasteners to help assemble the air bag module 12. The reaction plate 20may further include apertures 46 for helping to secure the air bagmodule 12 in the vehicle.

The air bag module 12 also includes a retainer 60 that cooperates withthe reaction plate 20 to help support the air bag 14 on the reactionplate. The retainer 60 is illustrated in FIG. 4. Referring to FIGS. 1,2, and 4, the retainer 60 is a single piece of material, such as metalor high strength plastic, that is formed to the generally rectangularconfiguration with rounded corner portions illustrated in FIG. 4. Itwill be appreciated that the retainer 60 could have a variety ofalternative configurations depending on various factors, such as thearchitecture of the vehicle in which the air bag module 12 is installedand the configuration of the reaction plate 20 with which the retainercooperates.

The retainer 60 has a main portion 62 with a rim or outer wall 64 thatextends about a periphery 66 of the reaction plate in a direction upward(as viewed in FIGS. 1 and 2) from the main portion 62. The main portion62 of the retainer 60 may be adapted to include openings 78 forreceiving fasteners 70, such as studs or bolts, thereby helping tosecure the retainer to the reaction plate 20. In the embodimentillustrated in FIG. 4, the retainer 60 includes four such openings 78positioned at or near respective corners of the retainer.

The retainer 60 also includes a generally cylindrical central portion 72with a central opening 74 for receiving a portion of the inflator 18. Inthe embodiment of FIGS. 1, 2, and 4, the central portion 72 is raisedfrom the main portion 62 of the retainer. The opening 74 has a generallycircular configuration that receives a cylindrical portion 76 of theinflator 18. The central opening 74 could, however, have a differentconfiguration for matching an inflator having a different construction.

The retainer 60 also includes a vent part 80 for blocking inflationfluid flow through the vent openings 40. In the embodiment shown in FIG.4, the retainer 60 includes a single vent part 80 that includes asupport portion 102 and a cover portion 84. The cover portion 84includes a centrally located actuator receiving opening 82. The coverportion 84 has portions shaped to mimic the wing-shaped configuration ofthe vent openings 40 and that are positioned on laterally opposite sidesof the opening 82. The configuration of the vent part 80 could, however,be altered, for example, to accommodate a particular configuration orarrangement of the vent openings 40.

The vent part 80 is partially defined by slots in the main portion 62 ofthe retainer 60 formed, for example, by cutting or stamping. A firstslot 92 helps define the overall wing-like shape or contour of the coverportion 84 of the vent part 80. The first slot 92 has spaced endportions 94 positioned along an edge 96 of the vent part 80. A pair ofsecond slots 100 are positioned between the end portions 94 and extendparallel to the edge 96.

The second slots 100 help define the support portion 102 of the ventpart 80 and three hinge portions 104 of the vent part. The hingeportions 104 extend from the cover portion 84 to the support portion 102and thereby connect the cover portion to the support portion.

In an assembled condition of the air bag module 12, the inflator 18 ispositioned such that the portion 36 extends through the opening 34 andthe portion 76 extends through the opening 74. In this position, aflange portion 110 of the inflator 18 is positioned between the mainportion 22 of the reaction plate 20 and the central portion 72 of theretainer 60. A mouth portion 112 of the air bag 14 is positioned betweenthe main portion 22 of the reaction plate 20 and the main portion 62 ofthe retainer 60.

In the assembled condition of FIGS. 1 and 2, the studs 70 extend throughrespective ones of the openings 44 in the reaction plate 20. Nuts 114are screwed onto the studs 70, which causes the reaction plate 20 andretainer 60 to exert a clamping force on the air bag 14 and the inflator18. The air bag 14 and inflator 18 are thus secured to the reactionplate 20 via the retainer 60.

The air bag module 12 also includes means for moving the vent part 80 inthe form of an actuator 120. In the embodiment illustrated in FIGS.1-5B, the actuator 120 comprises an actuatable fastener 122. Theactuator 120 could, however, have alternative configurations. Forexample, the actuator 120 could comprise an electromechanical device,such as a solenoid (not shown). As another example, the actuator 120could comprise a mechanical device, such as a spring loaded mechanism.

The actuatable fastener 122 includes a head portion 124 and a shankportion 126. Referring to FIGS. 5A and 5B, the shank portion 126includes a first shank portion 130 and a second shank portion 132. Thesecond shank portion 132 includes an annular shoulder portion 136 and isseparated from the first shank portion 130 by an annular groove 134.

The first shank portion 130 is secured to the main portion 22 of thereaction plate 20 via a threaded nut 140 that is connected to thereaction plate by means, such as a weld. The shank 126 extends throughthe opening 42 in the main portion 22 of the reaction plate 20. Thesecond shank portion 132 extends through the opening 82 in the coverportion 84 such that the shoulder portion 136 engages the cover portion.A nut 142 is screwed onto the second shank portion 132 to clamp thecover portion 84 between the shoulder portion 136 and the fastener. Thecover portion 84 and, thus the vent part 80, are secured to the secondshank portion 136 of the actuatable fastener 122.

The cover portion 84 of the vent part 80 is movable from an unactuatedcondition, illustrated in FIGS. 1 and 5A, to an actuated conditionillustrated in FIGS. 2 and 5B. In the unactuated condition, the coverportion 84 overlies the vent openings 40 and thus helps block fluid flowthrough the openings. In the actuated condition, the cover portion 84 ismoved away from the vent openings 40 and thus permits fluid flow throughthe openings.

The apparatus 10 also includes a controller 200 operatively connected tothe actuator 120 and to the inflator 18 by means 202, such as leadwires. The controller 200 is operative selectively to actuate theinflator 18 and/or the actuator 120. The apparatus 10 also includes oneor more sensors 204 operatively connected to the controller 200 viameans 206, such as lead wires. The sensors 204 are operative to supplysignals to the controller 200 indicative of sensed conditions, which thecontroller uses to determine whether to actuate the inflator 18 and/oractuator 120.

The sensors 204 may be operative to sense a variety of conditions of thevehicle and/or a vehicle occupant. For example, the sensors 204 mayinclude vehicle collision and/or rollover sensors, occupant positionsensors, seat position sensors, seat belt latch sensors, seat weightsensors, seat belt tension sensors, or any other sensors that may beuseful in determining whether to actuate the inflator 18 and/or actuator120.

Upon the occurrence of an event for which actuation of the inflator 18is desired, such as a vehicle collision, the controller 200 is operativeto actuate the inflator 18 to inflate the air bag 14. In this situation,the controller 200 is also operative selectively to actuate the actuator120 to move the cover portion 84 of the vent part 80 between theunactuated and actuated conditions. The controller 200 determineswhether to actuate the actuator 120 based on vehicle and occupantconditions sensed via the sensors 204. If, based on the conditionssensed via the sensors 204, the controller 200 determines the need toinflate the air bag 14 and maintain a relatively high inflation pressurefor the air bag, the controller is operative to maintain the vent part80 in the unactuated condition and thus does not actuate the actuator120. If, based on the conditions sensed via the sensors 204, thecontroller 200 determines the need to reduce the inflation pressure inthe air bag 14, the controller is operative to actuate the actuator 120to move the vent part 80 to the actuated condition to permit inflationfluid to vent from the air bag 14 through the vent openings 40.

For example, the sensors 204 may provide signals to the controller 200indicating that an occupant is in a normal seated position andrestrained by a vehicle seat belt. If this situation is detected, thecontroller 200 may be operative to actuate the actuator 120 to move thevent part 80 to the actuated condition and vent inflation fluid from theinflatable volume 16 of the air bag 14. This venting of inflation fluidmay provide a desired ride down effect for the inflatable curtain 14.

As another example, the sensors 204 may provide signals to thecontroller 200 indicating that an occupant is in a normal seatedposition but not restrained by a vehicle seat belt. If this situation isdetected, the controller 200 may be operative to actuate the inflator 18and block actuation of the actuator 120 so that the vent part 80 remainsin the unactuated condition. This prevents inflation fluid from ventingfrom the air bag 14, which allows the air bag to inflate fully andremain inflated throughout the duration of the collision. As a result,the air bag 14 may provide a high level of energy absorption for theunbelted occupant.

Those skilled in the art will appreciate that situations other thanthose set forth above may be sensed via the sensors 204 and used by thecontroller 200 to control operation of the inflator 18 and actuator 120.For example, the sensors 204 may provide information relating to sensedweight on the seat and sensed seat belt tension to estimate the size andposition of the occupant. The controller 200 may then further controlactuation of the inflator 18 and/or actuator 120 to provide the energyabsorption characteristics required for the sensed occupant. As anotherexample, seat belt tension and weight on the seat sensed by the sensors204 may be used to detect the presence of a child safety seat.

According to the present invention, when the actuator 120 is actuated toplace the cover portion 84 in the actuated condition, the vent part 80undergoes plastic deformation at the hinge portions 104. The plasticdeformation of the hinge portions 104 helps maintain the cover portion84 in the actuated condition of FIGS. 2 and 5B. As a result, the needfor additional means for maintaining the cover portion 84 in theactuated condition, such as latching mechanisms, can be eliminated.

Also, upon actuation of the actuator 120, the cover portion 84 moves ina direction upstream of the vent openings 40, i.e., in a directiongenerally into the inflatable volume 16 of the air bag 14. This isindicated generally by the arrow in FIG. 5B. Movement of the coverportion 84 in this direction can help avoid the need to provide aclearance for receiving the cover portion 84 in the area downstream ofthe vent openings 40. This may free up space for a variety of items,such as steering wheel structure and steering wheel mounted devices,such as electronics and switches.

The illustrated configuration of the vent part 80 may also beadvantageous in scenarios where the cover portion 84 remains in theunactuated condition during inflation of the air bag 14. In thesescenarios, the inflation fluid pressure in the inflatable volume 16 actson the cover portion 84 and urges the cover portion against the reactionplate 20, which helps block leakage of inflation fluid through the ventopenings 40.

A second embodiment of the present invention is illustrated in FIGS.6-7B. The second embodiment of the invention is similar to the firstembodiment of the invention illustrated in FIGS. 1-5B. Accordingly,numerals similar to those of FIGS. 1-5B will be utilized in FIGS. 6-7Bto identify similar components, the suffix letter “a” being associatedwith the numerals of FIGS. 6-7B to avoid confusion. The secondembodiment of the present invention is similar to the first embodiment(FIGS. 1-5B), except that the vent part of the second embodiment isformed as piece of material separate from the reaction plate andretainer.

Referring to FIGS. 6-7B, the air bag module 12 a includes a vent part250 formed as a single piece of high strength material, such as metal orplastic. The vent part 250 is separate from the reaction plate 20 a anda retainer 280 of the air bag module 12 a. The retainer 280 of thesecond embodiment is similar to the retainer 60 of the first embodiment,except that the retainer 280 includes an opening 282 for accommodatingthe vent part 250. The vent part 250 of the second embodiment isactuatable from an unactuated condition (FIG. 7A) to an actuatedcondition (FIG. 7B).

The vent part 250 includes a support portion 252 and a cover portion254. The cover portion 254 includes a centrally located actuatorreceiving opening 256. The cover portion 254 has portions shaped tomimic the wing-shaped configuration of the vent openings 40 a and arepositioned on laterally opposite sides of the opening 256. Theconfiguration of the vent part 250 could, however, be altered, forexample, to accommodate a particular configuration or arrangement of thevent openings 40 a.

The vent part 250 includes pair of slots 260 that help define thesupport portion 252 of the vent part 250 and three hinge portions 262 ofthe vent part. The hinge portions 262 extend from the cover portion 254to the support portion 252 and thereby connect the cover portion to thesupport portion.

Referring to FIGS. 7A and 7B, in an assembled condition of the air bagmodule 12 a, the flange of the inflator 18 a is positioned between thereaction plate 20 a and the retainer 280. A mouth portion 112 a of theair bag 14 a and the support portion 252 of the vent part 250 arepositioned between the reaction plate 20 a and the retainer 280.

In the assembled condition, the retainer 280 is secured to the reactionplate 20 a by means (not shown), such as the studs and nuts of the firstembodiment (see, e.g., FIGS. 1 and 2). In doing so, the reaction plate20 a and retainer 280 exert a clamping force on the air bag 14 a,inflator 18 a, and support portion 252 of the vent part 250. As aresult, the air bag 14 a, inflator 18 a, and vent part 250 are securedto the reaction plate 20 via the retainer 280.

The air bag module 12 also includes an actuator 120 a for actuating thevent part 250. The actuator 120 a may be an actuatable fastener securedto the vent part 250 and reaction plate 20 in a manner similar oridentical to the actuator 120 of the first embodiment, as describedabove. In the unactuated condition (FIG. 7A), the cover portion 254overlies the vent openings 40 a and thus helps block fluid flow throughthe openings. When the actuator 120 a is actuated to place the coverportion 254 in the actuated condition (FIG. 7B), the cover portion 254is moved away from the vent openings 40 a and thus permits fluid flowthrough the openings.

When the vent part 250 is placed in the actuated condition, the hingeportions 262 undergo plastic deformation. The plastic deformation of thehinge portions 262 helps maintain the cover portion 254 in the actuatedcondition. As described above, this may help avoid the need foradditional means, such as latching mechanisms, for maintaining the coverportion 254 in the actuated condition.

Also, in the second embodiment, upon actuation of the actuator 120 a,the cover portion 254 moves in a direction upstream of the vent openings40 a in a direction generally into the inflatable volume 16 a of the airbag 14 a. Movement of the cover portion 254 in this direction can helpavoid the need to provide a clearance in the area downstream of the ventopenings 40 a.

Further, in the second embodiment, the inflation fluid pressure in theinflatable volume 16 a acts on the cover portion 254 and urges the coverportion against the reaction plate 20 a, which helps block leakage ofinflation fluid through the vent openings 40 a.

From the above description of the invention, those skilled in the artwill perceive improvements, changes and modifications in the invention.Such improvements, changes and modifications within the skill of the artare intended to be covered by the appended claims.

1. An apparatus for helping to protect an occupant of a vehicle, saidapparatus comprising: an inflatable vehicle occupant protection device;an inflation fluid source actuatable to provide inflation fluid forinflating an inflatable volume of said inflatable vehicle occupantprotection device; a reaction plate including at least one vent opening;a retainer connectable with said reaction plate to clamp said inflatablevehicle occupant protection device between said reaction plate and saidretainer; a vent part having a first condition blocking inflation fluidflow through said at least one vent opening and a second conditionpermitting inflation fluid flow through said at least one vent opening;and actuatable means for moving said vent part from one of said firstand second conditions to the other of said first and second conditions,said vent part, when moved to the other of said first and secondconditions, being maintained in the other of said first and secondconditions by a plastically deformed portion of said vent part.
 2. Theapparatus recited in claim 1, wherein said vent part comprises a coverportion for blocking inflation fluid flow through said at least one ventopening in said first condition and for permitting inflation fluid flowthrough said at least one vent opening in said second condition, saidvent part further comprising a support portion supported by saidretainer, said portion of said vent part comprising a hinge portionconnecting said cover portion with said support portion, said hingeportion deforming to permit said cover portion to move between saidfirst and second conditions.
 3. The apparatus recited in claim 2,wherein said vent part comprises at least one slit extending throughsaid vent part that separates said cover portion from said supportportion, said at least one slit helping to define said hinge portion. 4.The apparatus recited in claim 3, wherein said hinge portion comprisesat least one strip of material connecting said support portion with saidcover portion.
 5. The apparatus recited in claim 2, wherein said hingeportion undergoes plastic deformation when said cover portion moves fromone of said first and second conditions to the other of said first andsecond conditions.
 6. The apparatus recited in claim 5, wherein saidhinge portion when plastically deformed maintains said cover portion insaid second condition against the pressure of said inflation fluid thaturges said cover portion toward said first condition.
 7. The apparatusrecited in claim 2, wherein said vent part comprises a piece of materialseparate from said reaction plate and said retainer, said supportportion being clamped between said reaction plate and said retainer. 8.The apparatus recited in claim 2, wherein said retainer and said ventpart are formed together as a single piece of material, said coverportion being defined by a slit that extends through said single pieceof material.
 9. The apparatus recited in claim 2, wherein said vent partis arranged such that pressure of said inflation fluid in saidinflatable volume acts on said cover portion to urge said cover portionagainst said reaction plate to help form a seal for helping to blockinflation fluid flow through said at least one vent opening when saidcover portion is in said first condition.
 10. The apparatus recited inclaim 1, wherein said means for moving comprises an actuator having afirst portion secured to said reaction plate and a second portionsecured to said vent part, said actuator being actuatable to move saidvent part from one of said first and second conditions to the other ofsaid first and second conditions.
 11. The apparatus recited in claim 10,wherein said actuator comprises an actuatable fastener.
 12. Theapparatus recited in claim 10, wherein said actuator in an unactuatedcondition maintains said vent part in said first condition, saidactuator in an actuated condition moving said vent part to said secondcondition.
 13. The apparatus recited in claim 1, further comprising acontroller operatively connected with said inflation fluid source andsaid actuatable means and at least one sensor operatively connected withsaid controller, said controller being operative selectively to actuatesaid inflation fluid source and said actuatable means based on at leastone signal supplied to said controller from said at least one sensor.14. The apparatus recited in claim 13, wherein said at least one sensorcomprises at least one of a vehicle collision sensor, a vehicle rolloversensor, an occupant position sensor, a seat position sensor, a seat beltlatch sensor, a seat weight sensor, and a seat belt tension sensor. 15.The apparatus recited in claim 13, wherein said controller is operativeto actuate said actuatable means in response to a signal indicative of aseat belt latched determination.
 16. The apparatus recited in claim 13,wherein said controller is operative to maintain said actuatable meansin an unactuated condition in response to a signal indicative of a seatbelt unlatched determination.
 17. The apparatus recited in claim 1,wherein said portion of said vent part is plastically deformed when saidvent part moves to said second condition, said plastically deformedportion maintaining said vent part in said second condition against thepressure of said inflation fluid that urges said vent part toward saidfirst condition.
 18. The apparatus recited in claim 1, wherein said ventpart comprises a piece of material separate from said reaction plate andsaid retainer, said vent part having a portion clamped between saidreaction plate and said retainer.
 19. The apparatus recited in claim 1,wherein said retainer and said vent part are formed together as a singlepiece of material, said vent part being at least partially defined by atleast one slit that extends through said single piece of material. 20.The apparatus recited in claim 1, wherein said vent part is arrangedsuch that pressure of said inflation fluid in said inflatable volumeacts on said vent part to urge said vent part against said reactionplate to help form a seal for helping to block inflation fluid flowthrough said at least one vent opening when said vent part is in anunactuated condition.
 21. An air bag module comprising: an air bag; areaction plate including at least one vent opening; a retainerconnectable with said reaction plate to clamp said air bag between saidreaction plate and said retainer; a vent part having a first conditionblocking inflation fluid flow through said at least one vent opening anda second condition permitting inflation fluid flow through said at leastone vent opening; and an actuatable fastener having a first portionsecured to said reaction plate and a second portion secured to said ventpart, said actuatable fastener being actuatable to move said vent partfrom one of said first and second conditions to the other of said firstand second conditions.
 22. The air bag module recited in claim 21,wherein said retainer comprises a single piece of material, said ventpart being at least partially defined in said retainer by a slitextending through said retainer.
 23. An air bag module comprising: anair bag; a reaction plate including at least one vent opening; and aretainer connectable with said reaction plate to secure said air bag tosaid reaction plate, said retainer including a vent part formed as asingle piece of material with said retainer, said vent part being atleast partially defined by a slit extending through said retainer, saidvent part having a first condition blocking inflation fluid flow throughsaid at least one vent opening and a second condition permittinginflation fluid flow through said at least one vent opening.